Follicular lymphoma: 2018 update on diagnosis and management.

DISEASE OVERVIEW: Follicular lymphoma is generally an indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma (FL) is characterized by diffuse lymphadenopathy, bone marrow involvement, splenomegaly and less commonly other extranodal sites of involvement. In general, cytopenias can occur but constitutional symptoms of fever, nightsweats, and weight loss are uncommon. DIAGNOSIS: Diagnosis is based on histology of preferably a biopsy of a lymph node. Immunohistochemical staining is positive in virtually all cases for cell surface CD19, CD20, CD10, and monoclonal immunoglobulin, as well as cytoplasmic expression of bcl-2 protein. The overwhelming majority of cases have the characteristic t(14;18) translocation involving the IgH/bcl-2 genes. RISK STRATIFICATION: The Follicular Lymphoma International Prognostic Index prognostic model for FL uses five independent predictors of inferior survival: age >60 years, hemoglobin <12 g/dL, serum LDH > normal, Ann Arbor stage III/IV, number of involved nodal areas > 4. The presence of 0, 1, 2, and ≥ 3 adverse factors defines low, intermediate, and high-risk disease. With the use of more modern therapies, outcomes have improved. RISK-ADAPTED THERAPY: Observation continues to be adequate for asymptomatic patients with low bulk disease and no cytopenias, with no survival advantage for early treatment with either chemotherapy or rituximab alone. For patients needing therapy, most patients are treated with chemotherapy plus rituximab, which has improved response rates, duration of response and overall survival. Randomized studies have shown additional benefit for maintenance rituximab both following chemotherapy-rituximab and single agent rituximab. Experimental therapies as well as stem cell transplantation (SCT) are considered for recurrent disease.